The siege of Capua was a military operation involving the states of medieval southern Italy, beginning in May 1098 and lasting forty days.
It was an interesting siege historically for the assemblage of great persons it saw and militarily for the cooperation of Norman and Saracen forces which it necessitated.
The siege was instigated by Richard II, prince of Capua, who had been exiled from his own capital for seven years (1091–1098) by Lando IV until, reaching his majority, he requested the aid of his great uncle, the count of Sicily, Roger I, and his first cousin once removed, the duke of Apulia, Roger Borsa.
According to Eadmer, many Arabs, impressed by tales of Anselm's holiness, visited his tent for food and other gifts.
It also assured the presence of an "outlet for the military instincts and talents of his Muslim subjects," according to historian John Julius Norwich.